Sorry that I neglected to mention that the round leaves and white flowers are the same plant, which is climbing up (vine) neighboring shrubbery with long, slender tendrils. I still think it may be a garden vegetable. I wish I had ginger growing!
Many species of small white and brown mushrooms have come up this summer in my garden beds. My watering regime has even awakened a small batch of large, edible Neolentinus mushrooms out of a railroad tie. If it weren't for the possibility of the wood having been soaked in creosote or another toxic chemical, they'd be culinary history by now!
